From today, CERN will be taking bookings for visits of its underground facilities during the Open Days. From 9am to 8pm on 28 and 29 September 2013, members of the public will have a rare opportunity to visit one of CERN's underground sites. Two points of the Large Hadron Collider (LHC), CERN’s flagship accelerator, will be open to visitors, as will its four main experiments and the Super Proton Synchrotron (SPS), another underground accelerator.

As the capacity for underground visits is limited, access to the underground facilities will be by reservation only, and tickets must be obtained from the CERN Open Days website. For safety reasons, children aged 12 or under will not be admitted to the underground sites. Each person will be able to reserve up to four tickets, which will be valid for a specific day and timeslot. The tickets, which are free of charge, will be made available on the site progressively over a four-week period.

CERN operates state-of-the-art scientific instrumentation, particle accelerators and detectors, in the pursuit of fundamental knowledge about matter and the universe. Its largest accelerator, the LHC, is an underground ring measuring 27 kilometres in circumference that smashes tiny particles into each other. Their collisions are analysed by several detectors, including in particular four huge machines measuring tens of metres in height and length, packed with millions of sensors. The LHC is fed by a chain of accelerators, the last of which is the Super Proton Synchrotron, housed in an underground tunnel measuring 7 kilometres in circumference.

As well as the underground facilities, the public will be able to discover 35 other exciting sites where CERN’s activities increase our knowledge, such as laboratories, the Computer Centre, accelerators and experiments accessible on the surface and technical facilities. Visitors will have the chance to meet scientists, engineers and technicians, who will explain the discoveries and technologies of the world's largest particle physics laboratory. 

All visits and activities will be free of charge.

In view of the large number of visitors expected, certain roads will be closed to traffic. No parking for the general public will be available on the CERN sites, so visitors are strongly recommended to use public transport and the shuttle-bus service provided for the event. These shuttle buses, for which there will be no charge, will make regular trips between the external car parks and the CERN visit sites. Each visitor will be entitled to a free ticket for one return trip to the Open Days, valid on all public transport within the Unireso Tout Genève zone, courtesy of our partner for the event Transport Publics Genevois (Geneva’s public transport system).

To reserve tickets for the underground visits and for practical information concerning all aspects of the Open Days, please consult the Open Days website.

Journalists wishing to attend the Open Days are invited to contact the CERN Press Office.